The invention relates to a portable, electric air humidifier, more particularly to an improved warm-air humidifier.
Air humidifiers have been found to be important in controlling the environment in homes during very dry weather, or in winter whenever outside air of low temperature is drawn inside and heated, causing the relative humidity in the home to be lowered to an uncomfortable degree.
Portable humidifiers are well known in the art, and may be classified as follows:
1. Steam generators which comprise a water container and an electric heating element submerged in the water, there being provided safety devices for switching off the current as soon as the water level drops below the heating element. A flow of hot steam is blown directly into the room to be humidified and there is always the danger of a person, especially a child, being scalded whenever he comes into contact with the jet of steam ejected, typically, at a temperature of about 212.degree. F. Furthermore, the container of hot water, when overturned, may cause serious injuries to the person nearby.
2. Porous medium humidifiers generally include a porous medium structure partly submerged in cold water contained in an open vessel and a blower unit drawing air through the porous medium structure. The porous medium is either in the shape of a disc or a drum with part of the medium dipping into the water, which is slowly rotated while air is blown through the portion above the water level, thus carrying humidity into the room; or it is in the form a stationary body adapted to draw water into the upper non-immersed part by capillary action, from where it is carried into the room by air blown therethrough.
3. Ultra-sonic humidifiers generally comprise a container filled with water which is brought to a vibration by high-frequency vibrator means which causes the water to be atomized. An air steam directed onto the water surface carries the mist into the room to be humidified.
The major drawback of both the two latter appliances is the fact that the water staying in the container is not heated to boiling point as in the steam generator and, therefore, is susceptible to the growth of microorganisms which are subsequently carried by the air stream into the room and ingested by the people staying there.
4. Warm-air humidifiers share the benefits of steam generators in that growth of micro-organisms is forestalled by heating the water to boiling point. Also, warm-air humidifiers avoid the drawback of hot steam entering the room, since in this type of humidifier the steam is carried into the room as a mist mixed with air, at a temperature to be selected by judiciously choosing the ratio of steam and air.
A typical warm-air humidifier is described in U.S. Pat. No. 4,564,746: it includes a heated evaporation chamber which is enclosed to prevent leakage or damage and a fan adapted for dispersing the generated steam into the room via a cabinet passageway. The evaporation chamber is mounted on tracks which permit its sliding out of its enclosure and is thus easily accessible for cleaning and servicing. The heating element which is operationally enclosed in the chamber is attached to a cover which is likewise movable out of the humidifier cabinet for cleaning and servicing.
The drawback of this humidifier is its relatively intricate and expensive design: according to the description, the heating element is attached to a movable cover which is provided with flexible tubing and must be moved upwards on vertical tracks in order to clear the top of the water enclosure, permitting the latter to be slide out sideways. It requires a significant amount of space and cannot be serviced except by a skilled person.
The humidifier disclosed in applicant's U.S. Pat. No. 5,014,338 and pending patent application Ser. No. 07/606,938, now U.S. Pat. No. 5,111,529, and in the present application have similar or substantially the same structure except as will be brought out hereinafter. For one thing, a steam ejector is provided in the present application which takes the place of the motor driven blower disclosed in applicant's mentioned patent and pending application. In terms of similar concepts and structure which are common to the mentioned patent, pending application and present application, the various embodiments each employs base means having a water supply compartment separated into a filling compartment and a main compartment which is in communication with an evaporation chamber to provide water thereto for boiling. The evaporation chamber has an enclosure which projects into the main compartment and a heater is carried within the enclosure. The lower edges or the wall of the enclosure is spaced from the floor of the main compartment to form a passageway, whereby water flows therethrough to immerse the heater within the water. Structure, either in the form of removable trays or a displaceable housing containing the evaporation chamber, is utilized to obtain access to the trays or the heater for cleaning purposes.
Humidifiers employing motor driven blowers, such as is found in applicant's U.S. Pat. No. 5,014,338 and in pending application Ser. No. 07/606,938, now U.S. Pat. No. 5,111,529, have many benefits and advantages. On the other hand, the use of warm air humidifiers utilizing motor driven blowers are at times deemed objectionable when used in nurseries and in bedrooms as being non-conducive to sleep because of the mechanical and aerodynamic noise associated with motor driven blowers. In addition, the presence of high humidity to which motor shafts are exposed creates rusting problems with the resulting binding of the shafts to the bearings. Obviously, this creates expensive maintenance problems and may inhibit the user from obtaining service because of the expense.
Certain criteria are desired in warm air humidifiers to maximize the desirability and efficiency of such devices for the user. One criterion is to maintain the steam-air mixture at a predetermined temperature which ranges between 37.degree. C. and 65.degree. C. (99.degree. F.-149.degree. F.) where the lower end of the range approximates human body temperature and the upper end represents a value at which the steam air mixture still may be brought into contact with a person's hand without the sensation of pain. Another criterion is to provide a uniform mixing of air and steam resulting in an even temperature profile at the outlet grille and avoiding non-uniform degrees of air saturation as well as local recondensation on portions of the grill.
The following relevant prior art has been found in a patentability search: U.S. Pat. No. 4,635,630; Soviet documents no's. SU1174569A and 883,637.
Accordingly it is an object of the present invention to provide an improved and novel non-motor driven warm-air humidifier which utilizes a simple and inexpensive structure and still obtains results equivalent to or better than those obtained by humidifiers employing motor driven blowers.
It is another object to provide an improved and novel humidifier which provides for the proper and uniform mixture of steam laden air having the proper ratio of air and steam and substantially uniform temperature profile at the outlet grille.
It is a further object to provide an improved and novel humidifier which employs a steam ejector in place of a motor driven blower and which exhibits significantly less objectionable noises than those employing motor driven blowers.
It is a still further object to provide a novel and improved humidifier which utilizes a steam ejector tube having a restricted throat portion therein and which is dimensioned and positioned in relation to a steam nozzle in which steam flows at a certain velocity and produces a air-steam mixture of the proper saturation and temperature substantially noise free or of minimum noise.
Another object is to provide a novel and improved gravity water-feed humidifier in which the constant pressure to drive the generated steam through a steam nozzle is maintained by a differential head of water existing between the stream generation compartment and the water supply compartment.
Further objects ad advantages of the present invention will become obvious to one skilled in the art in the following description of the invention and the claims.